Complete Object-Oriented JavaScript example (ES5).

oojs_es5.js

function Person(first, last, age, gender, interests) {
  this.name = {
    first,
    last
  };
  this.age = age;
  this.gender = gender;
  this.interests = interests;
};

function Teacher(first, last, age, gender, interests, subject) {
  Person.call(this, first, last, age, gender, interests); // The call() method calls a function with a given this value and arguments provided individually.

  this.subject = subject;
}
Teacher.prototype = Object.create(Person.prototype); // The Object.create() method creates a new object, using an existing object as the prototype of the newly created object.
Teacher.prototype.constructor = Teacher;

Teacher.prototype.greeting = function() {
  var prefix;

  if (this.gender === 'male' || this.gender === 'Male' || this.gender === 'm' || this.gender === 'M') {
    prefix = 'Mr.';
  } else if (this.gender === 'female' || this.gender === 'Female' || this.gender === 'f' || this.gender === 'F') {
    prefix = 'Mrs.';
  } else {
    prefix = 'Mx.';
  }

  alert('Hello. My name is ' + prefix + ' ' + this.name.last + ', and I teach ' + this.subject + '.');
};